Tungsten resistance elements



July 7, 1964 M. TURKAT 3,140,460

' TUNGSTEN RESISTANCE ELEMENTS Filed Oct. 16, 1961 FIG. I.

INVENTOR MICHAEL TURKAT ATTO RNEY.

United States Patent 3,140,460 TUNGSTEN RESISTANCE ELEMENTS Michael Turkat, Bayside, N.Y., assignor to Space Age Materials Corp., Woodside, N.Y. Filed Oct. 16, 1961, Ser. No. 145,323 3 Claims. (Cl. 338-309) This invention relates to electrical resistors and to processes utilized in their manufacture.

Carbon and metal film resistors are known which are unable to withstand excessively high temperatures and voltages.

An object of the invention is to provide metal film resistors capable of withstanding excessively high temperatures and voltages.

Another object of the invention is to provide metal film resistors whose resistance will increase as additional power is applied thereto.

A further object of the invention is to provide a metal film resistor whose resistance increases with power applied for the purpose of regulating electric current and power.

A feature of the invention is a tungsten film resistor whose resistance increases with the electrical power applied thereto.

Another feature of the invention is a high precision tungsten film resistor formed by the deposition of tungsten, or from the cracking of tungsten bearing gases in a high temperature furnace containing inert media.

Another feature of the invention is a high precision tungsten film resistor deposited on a ceramic or steatite form.

The invention will be more fully understood by reference to the following detailed description and to the accomp anying drawings wherein,

FIGURE 1 is an elevational view partially broken away of a metal film resistor in accordance with the invention.

FIGURES 2-4 show various sectional views of the resistor assembly of FIGURE 1 in accordance with the invention.

In general, the film resistor involves an insulation core with a deposited coating of tungsten metal thereon, which is able to withstand higher temperatures and higher voltages than conventional metal film or carbon resistors.

The resistance of tungsten film increases as additional electrical power is applied thereto. It will tend to behave similar to an electric light bulb and can be used as a current or power regulator.

Referring to FIGURE 1 of the drawing, a ceramic or steatite core 1 has a film 2 of tungsten metal deposited thereon. The tungsten deposit may be derived from a tungsten vapor or by cracking a mixture of tungsten bearing gases in a high temperature furnace. The excess of other gases in the furnace is carried away in any suitable manner, and pure crystalline tungsten film'2 deposits on to the ceramic core 1, either from the tungsten vapor or as a result of the cracking of the tungsten bearing gases.

Tungsten and other metallic vapors can be blended together to provide a wide variety of self-varying resistance elements. Also layers of different metals, including tungsten, may be applied to the ceramic substrate 1 either as separate coats, or blended or alloyed with the tungsten.

3,140,460 Patented July 7, 1964 Suitable metals for this purpose may be iridium, chromium, platinum, tantalum and the like.

It should be appreciated that the ceramic core 1 coated with a continuous tungsten film deposited thereon, maybe used in this manner per se. However, where it is desired to provide precision resistors, the deposited tungsten film or coating may be cut or ground down appropriately to provide a spiral resistance element 2 whenever it becomes necessary to provide an increased path length in the resistance element.

The oxidation of the tungsten resistor at high temperatures is prevented by an aluminum silica glaze 3, applied to the tungsten resistance element, thereby providing it with a protective coating.

End caps or terminals 4 are provided for the resistance element shown in FIGURE 1, which are fitted over the ceramic core 1 and contact the tungsten coating 2. In bonding metal caps 4 to the ceramic core 1, it is preferable to utilize high temperature firing therefor.

Tinned copper leads 5 are connected to the terminals 4. Gold bands physically and electrically connect the resistance coating 2 to the terminals 4.

Various types of thin covers 6 may be applied over the core 1 and terminals 4. The protective coverings may be flexible, pliant or rigid as required. Various suitable materials for the covering are plastics, such as, polyethylene, polyvinyl thermosetting resin compositions molded over the core 1 and tungsten film 2.

Also, ceramic tubes or hermetically sealed shells 7 may be used as protective coverings fitting on the end caps 4 and covering the resistance element 2 located therebetween.

Various different embodiments of my invention may be made without departing from the spirit and scope thereof as will be apparent to those skilled in the art to which this invention pertains. It should be understood that my invention is not limited only to the specific embodiments described except as defined in the appended claims.

What I claim is:

1. A resistance element comprising an insulation core, a tungsten-containing vapor deposited metal film thereon whose resistance increases with the electric power applied, end terminals in contact with said metal film, a thin plastic protective cover extending over said resistance element from end to end, tinned copper leads connected to said terminals, and gold bands for connecting each of said terminals to said metal film.

2. The resistance element of claim 1, wherein the tungsten of said metal film is deposited from the cracking of tungsten bearing gases at high temperature.

3. The resistance element of claim 1, wherein said plastic protective cover comprises a silica glaze to prevent the oxidation of the tungsten.

References Cited in the file of this patent UNITED STATES PATENTS 792,638 Whitney June 20, 1905 1,093,792 Madsen Apr. 21, 1914 2,803,729 Kohring Aug. 20, 1957 2,962,393 Ruckelshaus Nov. 29, 1960 3,013,328 Beggs Dec. 19, 1961 3,018,198 Olson et al. Jan. 23, 1962 

1. A RESISTANCE ELEMENT COMPRISING AN INSULATION CORE, A TUNGSTEN-CONTAINING VAPOR DEPOSITED METAL FILM THEREON WHOSE RESISTANCE INCREASE WITH THE ELECTRIC POWER APPLIED, END TERMINALS IN CONTACT WITH AID METAL FILM, A THIN PLASTIC PROTECTIVE COVER EXTENDING OVER SAID RESISTANCE ELEMENT FROM END TO END, TINNNED COPPER LEADS CONNECTED TO SAID TERMINALS, AND GOLD BANDS FOR CONNECTING EACH OF SAID TERMINALS TO SAID METAL FILM. 